(ad 869-883), a black-slave revolt against the 'Abbasid
caliphal empire. A number of Basran landowners had brought
several thousand East African blacks (Zinj) into southern Iraq to
drain the salt marshes east of Basra. The
landowners subjected the Zanj, who generally spoke no Arabic, to
heavy slave labour and provided them with only minimal
subsistence. In September 869, 'Ali ibn Muhammad,
a Persian claiming descent from 'Ali, the fourth
caliph, and Fatimah, Muhammad's
daughter, gained the support of several slave-work crews--which
could number from 500 to 5,000 men--by pointing out the injustice
of their social position and promising them freedom and wealth.
'Ali's offers became even more attractive with his subsequent
adoption of a Kharijite religious stance: anyone, even a black
slave, could be elected caliph, and all non-Kharijites were
infidels threatened by a holy war.

Zanj forces grew rapidly in size and power, absorbing the
well-trained black contingents that defected from the defeated
caliphal armies, along with some disaffected local peasantry. In
October 869 they defeated a Basran force, and soon afterward a
Zinj capital, al-Mukhtarah (Arabic: the Chosen),
was built on an inaccessible dry spot in the salt flats,
surrounded by canals. The rebels gained control of southern Iraq
by capturing al-Ubullah (June 870), a seaport on
the Persian Gulf, and cutting communications to Basra, then
seized Ahwaz in southwestern Iran. The caliphal
armies, now entrusted to al-Muwaffaq, a brother
of the new caliph, al-Mu'tamid (reigned
870-892), still could not cope with the rebels. The Zinj sacked Basra
in September 871, and subsequently defeated al-Muwaffaq
himself in April 872.

Between 872 and 879, while al-Muwaffaq was
occupied in eastern Iran with the expansion of the Saffarids,
an independent Persian dynasty, the Zinj seized Wasit (878)
and established themselves in Khuzistan, Iran.
In 879, however, al-Muwaffaq organized a major
offensive against the black slaves. Within a year, the second
Zinj city, al-Mani'ah (The Impregnable), was
taken. The rebels were next expelled from Khuzistan,
and, in the spring of 881, al-Muwaffaq laid
siege to al-Mukhtarah from a special city built
on the other side of the Tigris River. Two years later, in August
883, reinforced by Egyptian troops, al-Muwaffaq
finally crushed the rebellion, conquering the city and returning
to Baghdad with 'Ali's head.